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MathGroup Archive 2001

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Re: how to round value in matrixs

  • To: mathgroup at smc.vnet.net
  • Subject: [mg31886] Re: how to round value in matrixs
  • From: "Allan Hayes" <hay at haystack.demon.co.uk>
  • Date: Sun, 9 Dec 2001 06:07:10 -0500 (EST)
  • References: <9usrvq$ckn$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

David,
Just a small point:
We don't need Map, since Round is Listable and N is pretty aggressive, for
example

    N[HoldComplete[{{Pi}}]]

         HoldComplete[{{3.14159}}]

Thus:

    round[n_][num_] := N[Round[10^n*num]/10^n]

    mat = Array[Random[] &, {2, 2}]

        {{0.374869,0.745659},{0.142273,0.397676}}

    roundedmat = round[3][mat]

        {{0.375,0.746},{0.142,0.398}}


--
Allan

---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565


"David Park" <djmp at earthlink.net> wrote in message
news:9usrvq$ckn$1 at smc.vnet.net...
> Tomasz,
>
> Here is a function which will round an approximate number to n places.
>
> round[n_][num_] := N[Round[10^n*num]/10^n]
>
> Here is a randomly generated matrix.
>
> mat = Array[Random[] &, {2, 2}]
> {{0.39248, 0.541335}, {0.236583, 0.330804}}
>
> This rounds the matrix elements to 3 places (by Mapping round[3] onto the
> elements of mat at level 2).
>
> roundedmat = Map[round[3], mat, {2}]
> {{0.392, 0.541}, {0.237, 0.331}}
>
> David Park
> djmp at earthlink.net
> http://home.earthlink.net/~djmp/
>
> > From: Tomasz [mailto:tomaszmach at poczta.onet.pl]
To: mathgroup at smc.vnet.net
> >
> > Hi
> > I use Mathematica 4.0 and I would like to know how I can to round matrix
> > values becouse I calculate in Mathematica matrix which include number
with
> > 13 digits after point but a would like to 3 digits after point
> > how do this .
> > thanks for all
> >
> >
> >
>
>




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